1. Field of the Invention
The present invention relates to systems and methods for auto-reversing loop polarity, and specifically to a system and method for auto-reversing loop polarity of a U interface.
2. Description of Related Art
In a conventional integrated services digital network (ISDN), user terminals are usually connected to a line terminal via a digital service unit, and are connected to an exchange terminal via the line terminal. The digital service unit is connected to the line terminal via a U interface.
However, the digital service unit is usually manually assembled, and it may abnormally communicate with the line terminal while a loop polarity of the U interface is incorrect. Thus, the user terminal cannot work normally, and users need to reverse the loop polarity of the U interface, which may be inconvenient and unsuitable.
Therefore, a heretofore unaddressed need exists in the industry to overcome the aforementioned deficiencies and inadequacies.